Terraform vs CDK

Both tools define infrastructure as code. The difference is where abstraction lives.

Terraform = declarative IaC language and ecosystem
CDK       = infrastructure defined in general-purpose code

Neither is universally better. The tradeoff is readability, abstraction, and ecosystem fit.

Terraform

Terraform uses HCL and has a very large provider ecosystem.

Pros:

• cloud-agnostic
• mature community and modules
• readable declarative diff model
• easier for infra teams to standardize

Cons:

• abstractions can get clunky
• loops and composition are weaker than real programming languages
• large monolithic states can become painful

Terraform is great when:

• infra spans multiple providers
• platform teams want a common standard
• teams value explicit plans and simple review diffs

CDK

CDK uses TypeScript, Python, Java, or other languages to generate CloudFormation.

Pros:

• real programming language abstractions
• easy reuse of functions, classes, and config
• strong fit for app teams already living in TypeScript/Python

Cons:

• can become "too clever"
• generated CloudFormation can be harder to reason about
• primarily AWS-focused

CDK is great when:

• you are strongly AWS-centric
• app engineers own a lot of their own infrastructure
• you want reusable constructs in normal code

Key Decision Points

Ecosystem

• Terraform wins for multi-cloud and breadth of providers
• CDK wins for AWS-native developer ergonomics

Reviewability

• Terraform usually produces clearer infra diffs
• CDK can hide changes behind abstraction unless teams are disciplined

Abstraction

• CDK is more expressive
• Terraform encourages simpler, more explicit infra definitions

Team Skill Set

• infra/platform-heavy orgs often prefer Terraform
• app-heavy AWS orgs often enjoy CDK

Common Hybrid Pattern

Some teams use:

• Terraform for foundational platform resources
• CDK for application-specific AWS stacks

This can work, but be careful about ownership boundaries and duplicated state.

Failure Modes

• Terraform: giant states, over-modularization, weak ownership
• CDK: abstraction for abstraction's sake, logic-heavy constructs, generated changes that reviewers do not understand

The tool is usually not the problem. Unclear boundaries are.

Interview Answer

Terraform vs CDK?

Terraform is better when you want cloud-agnostic, declarative, review-friendly infrastructure with a broad ecosystem. CDK is better when you are AWS-focused and want to model infrastructure with reusable abstractions in a general-purpose language. Pick based on team workflow and platform scope, not trendiness.